Ivan Pavlov

Ivan
Petrovich Pavlov (September 14, 1849 - February 27, 1936), Russian physiologist
who first described the phenomenon now known as conditioning in experiments with
dogs. He was awarded the Nobel Prize in Physiology or Medicine in 1904.

Pavlov
was investigating the gastric function of dogs, by externalising a salivary gland
so he could collect, measure, and analyse the saliva produced in response to food
under different conditions. He noticed that the dogs tended to salivate before
food was actually delivered to their mouths, and set out to investigate this "psychic
secretion", as he called it. He correctly decided that this was more interesting
than the chemistry of saliva, and changed the focus of his research, carrying
out a long series of experiments in which he manipulated the stimuli occurring
before the presentation of food. He thereby established the basic laws for the
establishment and extinction of what he called "conditional reflexes" - i.e. reflex
responses, like salivation, that only occurred conditional upon specific previous
experiences of the animal. These experiments were carried out in the 1890s and
1900s, and were known to western scientists through translations of individual
accounts, but first became fully available in English in a book published in 1927.

Perhaps unfortunately,
Pavlov's phrase "conditional reflex" was mistranslated from the
Russian as "conditioned reflex", and other scientists reading
his work concluded that since such reflexes were conditioned, they must be produced
by a process called conditioning. As Pavlov's work became known in the West, particularly
through the writings of John B. Watsn, the idea of "conditioning" as an automatic
form of learning became a key concept in the developing specialism of comparative
psychology, and the general approach to psychology that underlay it, behaviorism.
Bertrand Russell was an enthusastic advocate of the importance of Pavlov's work
for philosophy of mind.

Unlike
many pre-revolutionary scientists, Pavlov was highly regarded by the Soviet government,
and was able to continue his researches until he was a considerable age. In later
life he was particularly interested in trying to use conditioning to establish
an experimental model of the induction of neurosis. His laboratory in Moscow has
been carefully preserved.

It
is popularly believed that Pavlov always signalled the occurrence of food by ringing
a bell. In fact his writings record the use of a wide variety of auditory stimuli,
including whistles, metronomes, tuning forks and the bubbling of air through water,
in addition to a range of visual stimuli. When, in the 1990s, it became easier
for Western scientists to visit Pavlov's laboratory in Moscow, no trace of a bell
could be found.